# mcp.policy.Builder.environment_values

- **Module:** mcp.policy.Builder
- **Package:** tmux-mcp
- **Language:** Rust
- **Kind:** method
- **Source:** https://github.com/libtmux/libtmux-rs/blob/f0e37052c232636b61d095817046e6bfc8f2ca40/crates/tmux-mcp/src/policy.rs#L365
- **Page:** https://libtmux.org/en/rs/latest/mcp/reference/mcp-policy-builder-environment_values/

```
mcp.policy.Builder.environment_values(mut, names: BTreeSet<String>) -> Self
```

Allow tools to return the values of these tmux environment variables.

None are allowed by default: `show_environment` reports names and
state, and `get_tmux_variables` refuses a name the environment holds.
A tmux server inherits the environment of the shell that started it,
so its values are the user's tokens and keys.